This invention relates to electromagnetic projectile launchers and more particularly to such launchers having parallel projectile launching rails and using multiple plasma drives.
Parallel rail electromagnetic launchers which utilize a single pair of projectile rails require very high currents to achieve projectile velocities in excess of those obtained with conventional accelerating means such as explosives. In order to achieve a given accelerating force with a lower current, various augmentation schemes have been proposed. External augmentation is accomplished by placing additional conductors outside of the bore to increase bore flux and thereby increase the force exerted by a given current level in the armature or driving plasma. Only this type of augmented configuration has previously been considered suitable for arc or plasma drive because there is only a single arc driving the projectile or sabot and hence no possibility of parallel arcs at different potentials unfavorably fusing into a single arc.
Internally augmented launchers have additional conductors disposed along the interior of the bore. These launchers have previously only been considered viable with conducting armatures because internal series augmentation requires more than one conducting path or loop through the armature assembly. In addition, each of these multiplicity of paths in the prior art is at a different potential from the adjacent one and must be insulated from it. Since conducting armatures have only been demonstrated for velocities below about 1000 meters per second, internal series augmentation launchers have been relegated to larger bore artillery, torpedoes, missile launching, etc., all relatively low velocity systems.
For a given number of conductor pairs, internal series augmentation results in the highest force increase at a given current and yields the greatest current reduction compared to a simple parallel rail launcher operated at the same propelling force. Thus internal series augmentation is highly desirable from high propelling force and current reduction considerations, but the deemed impossibility of insulatably operating parallel arcs at different potentials against the rear face of a driving sabot has inhibited consideration of internally series augmented launchers using plasma drive.
Electromagnetic projectile launchers constructed in accordance with this invention include multiple parallel conductor pairs disposed along the perimeter of the launcher bore. Multiple plasmas which serve as conduction paths between these conductors provide means for propelling a projectile along the conductors. Means for preventing the merger of the multiple plasmas include insulating plasma dividers extending from an insulating sabot. In an internally series augmented conductor configuration, a source of high current supplies current to a conductor system connected such that current in adjacent conductors flows in the same direction. Alternatively, the conductors can be connected such that current in adjacent conductors flows in the opposite direction.
The potential different between adjacent conductors is minimized in an alternative embodiment through the use of multiple sources of high current wherein each pair of conductors and the associated plasma are supplied by an independent current source. Conducting elements which extend between the conductor pairs but have ends which are spaced a preselected distance from the conductors are attached to the driving sabot to reduce the total plasma length and volume between the conductors. U.S. Pat. No. 4,467,696, issued Aug. 28, 1984 and entitled "Electromagnetic Launcher With Combination Plasma/Conductor Armature", discloses a single current path armature launcher and is hereby incorporated by reference.